“Plants know how to make food and medicine from light and water, and then give it away.”
- Robin Wall Kimmerer, Braiding Sweetgrass
Have you ever wondered why tea drinkers always seem so calm? A cup of tea can lift mood, improve focus, reduce anxiety, and perhaps ward off dementia.
That’s because tea contains a unique combination of caffeine and a non-protein amino acid called theanine (also known as L-theanine). Only found in tea and a rare mushroom, theanine may be the best-kept secret behind tea drinkers’ calm happiness.
These two ingredients have an extraordinary effect on the brain. L-theanine has a very calming effect, while caffeine is a stimulant. L-theanine modulates caffeine, reducing its jittery effects and promoting a calm, focused state of mind.
I’m referring to the Camellia sinensis plant’s black, green, white, and oolong tea. This tea differs from herbal tea, an infusion made from any other plant called tisanes.
Of all the thousands of plants to choose from, why is this one tea plant the most popular beverage in the world? It’s not the caffeine. The coffee plant contains more caffeine, but more people worldwide drink tea than coffee.
Why do we drink millions of cups of tea a day?
L-theanine in tea
There’s something in the tea plant only found in two natural places: tea and a rare mushroom called the bay bolete. Scientists identified this rare and unique amino acid as L-theanine.
What exactly does L-theanine do that has millions of people drinking tea?
Researchers sought to answer this very question. The Brain and Cognition Laboratory at Oxford University in the UK studied L-theanine's ability to induce a relaxed, alert mental state.
Participants were connected to an electroencephalogram (EEG) to measure their brainwave activity—specifically, their alpha wave activity.
A brief overview of human brain activity
Human beings exhibit four primary mental states as measured by EEG. Brain waves are measured in hertz (symbol: Hz) in the International System of Units (SI). One hertz is equivalent to one cycle per second.
Two sleeping states:
1. Delta waves are when the entire electrical brain activity cycles slowly at about a wave per second and occur during deep sleep. The frequency range is 1-4 Hz.
2. Theta waves occur during dream sleep and deep relaxation and cycle at about five waves per second. The frequency range is 4-8 Hz.
Two waking states:
1. Alpha waves are present in a relaxed, aware, and attentive state. Similar to a meditative state. The frequency range is 8-12 Hz.
2. Beta waves dominate during the stimulated hustle and bustle state, where we spend most of our waking lives. The frequency range is 13-30 Hz.
The alpha state is where you want to be - fully alert and calm. But how do you get there?
If you relax in a lovely, peaceful place after about 90 minutes, you can see a significant increase in alpha brain waves. Think of a quiet afternoon at your favorite beach or a pleasant long nature walk at sunrise.
Meditating Buddhist monks can achieve this state sooner and maintain it with open eyes. So you can meditate daily for a few years or drink some tea.
This is your brain on tea
The study team from Oxford noted:
“L-theanine significantly increases activity in the alpha frequency band, which indicates that it relaxes the mind without inducing drowsiness.”
The Oxford study participants rested with their eyes closed during EEG recordings of their alpha brain wave activity.
The amount of L-theanine that enters your brain, crossing the blood-brain barrier after drinking two cups of tea, is about 50 mg. Look at the effects of L-theanine after drinking the equivalent of two cups of tea.
The orange area is the presence of alpha wave activity. See the difference?
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Can a cup of tea reduce anxiety?
I asked some of my readers about their experience with L-theanine in tea, whether they found it beneficial, and in what ways.
In an email interview, Wendy tells me she likes drinking tea and meditating. She says it’s the “perfect combination.” Wendy explains, “My husband has a depressive disorder, and drinking tea helps sort him out; (he) feels relaxed and a little more positive after.”
Wendy and her husband’s positive experience with drinking tea is quite common.
Another reader shares her experience, “I have anxiety, panic disorder, and ADHD, so that I can share my experience. It kinda helps with ADHD by slowing down my mind a bit, but I didn’t experience much else.”
She said, “It can help with mild anxiety and possibly prevent a panic attack if you catch it soon enough, but it barely helps bad anxiety for me. I would encourage people to try it, though, because everyone is different, and they might have a profound benefit from it.”
Tea for anxiety
Michelle Francl, author of Steeped: The Chemistry of Tea, writes,
“Studies have shown that L-theanine can reduce anxiety, improve cognition, reduce blood pressure, improve the quality of sleep, and, like caffeine, has neuroprotective properties...”
This is because L-theanine crosses the blood-brain barrier and affects the central nervous system.
This increase in alpha activity supports L-theanine’s role in achieving a relaxed mental state by directly influencing the central nervous system. Combining L-theanine with caffeine makes tea a unique beverage that promotes mental focus, increases energy, and reduces anxiety and stress.
Clinical trials have shown that theanine reduces anxiety and induces calm because it increases the neurotransmitters that balance our moods and control serotonin and dopamine, making us feel good.
Another study, published in 2020 in Plant Foods for Human Nutrition, reviewed available data on L-theanine’s effects on cognition and mood in humans and evaluated its effects on anxiety and stress.
The researchers found that L-theanine can reduce the stress response in people with mild anxiety. However, it is not as effective in lowering clinical-level anxiety.
The effective doses reported in the 2020 review of studies range from 200 to 400 mg. The Oxford study used only 50 mg of L-theanine and observed a difference in alpha brainwave activity. Depending on the tea and brewing process, a cup of tea can contain 8-46 mg of L-theanine.
Benefits of L-theanine in tea
Scientific evidence in these studies suggests that drinking tea provides many theanine benefits:
Increased cognitive function. It turns out tea may have a role in protecting our brains. The American Journal of Clinical Nutrition shows that regular tea consumption is associated with a lower risk of cognitive impairment and decline.
Lower blood pressure. The Journal of Physiological Anthropology reports that L-theanine reduces anxiety and lessens the blood pressure increase in high-stress response in healthy adults.
Improved mood. The University of Oxford study showed that theanine in tea elevates mood, reduces stress, and promotes relaxation.
Increased alertness. The same Oxford study showed that theanine balances the stimulatory effects of caffeine, so you stay alert without feeling jittery.
Improves attention span. A study published in Nature showed the natural combination of L-theanine and caffeine may result in short-term improvements in concentration and overall cognitive performance among boys with ADHD (attention deficit hyperactivity disorder).
How much L-theanine is in a cup of tea?
Certain teas have higher amounts of L-theanine than others. Green teas, grown in the shade for three weeks before harvest, have some of the highest L-theanine levels.
The shading increases the plants’ chlorophyll levels and simultaneously increases L-theanine uptake from the root system.
Shade-grown green teas include matcha, gyokuro, and tencha. The abundance of L-theanine also adds a taste of sweetness, earthiness, and umami to green tea.
“Growing conditions affect the amount of theanine produced in a given tea plant. Teas grown in sunnier conditions produce less theanine. First flushes will have more theanine than later flushes because the theanine that has spent the winter stored in the roots is transported to the early shoots, leaving less for sprouts that appear later in the season.”
—Michelle Francl, Steeped: The Chemistry of Tea
Brewing time is a significant factor in the amount of theanine extracted. Also, the type of tea leaves used may vary in theanine and caffeine content. Food Chemistry reports that adding small amounts of milk and sugar makes no significant difference.
Theanine in Black tea: A standard 6-ounce cup of black tea contains 24.2 milligrams of theanine.
Theanine in Green tea: A cup of green tea contains the least 7.9 milligrams of theanine.
Theanine in Shade-grown green tea: Matcha and Gyokuro may have as much as 46 milligrams of theanine per cup.
Are L-theanine supplements beneficial?
You can buy L-theanine supplements over the counter at 100 mg per tablet. Because the tablets are caffeine-free, some people take them to relax before sleep.
But the magic lies in the tea rather than pure L-theanine. Tea contains many different chemicals, all acting synergistically with one another. You know a lot is going on in that little tea leaf when someone can write an entire book on the chemistry of tea.
Isolating the active chemical elements from natural remedies is equivalent to capturing the information but discarding the wisdom. Nature is designed to take the whole leaf, not isolate the chemical components, for its remedy.
Positive L-theanine effects
Perhaps many people choose tea over coffee to reach that super calm and alert alpha state of mind. Or maybe they do it to reduce anxiety with the help of the calming effects of L-theanine on the brain. It doesn’t matter if you drink tea for anxiety or happiness; there are many positive benefits.
There are so many reasons to drink tea. No wonder tea has been used as a restorative beverage in traditional Chinese medicine for thousands of years.
How about you? If you drink tea, do you experience the calming and focused effects of L-theanine?
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